Simulation study on NO-reduction by volatiles from coal devolatilization

Study of nitric oxide (NO) reduction process by volatiles from coal devolatilization, based on the detailed chemical kinetic mechanism (1006 reversible reactions and 145 species), was performed in a plug flow reactor (PFR) of the chemical kinetic simulation package Chemkin 4.1 in the simulated reburning conditions. The main process parameters, such as gas temperature and equivalence ratio ware studied and the influences of sulfur contained volatile species on NO reduction were also explored. The PFR simulation results show that, for a given equivalence ratio, reaction temperature higher than 1100 K does not benefit NO reduction and the optimum temperature is 1100 K for NO reduction by coal volatiles at equivalence ratio 1.25. For a given temperature, with the increasing of equivalence ratio, NO reduction efficiency increases and HCN and NH₃ concentrations also increase while N₂ decreasing. The optimum NO reduction range of equivalence ratio is from 1.2 to 1.6 at temperature of 1200 K. For all tested cases, the effects of H₂S and SO₂ in volatiles on NO reduction efficiency are less than 5% compared with the tests of no sulfur contained volatile species involved, and H₂S has more influences on NO removing efficiency than SO₂.